gemstone

Carnelian

SiO2 (Silicon Dioxide with Iron Oxide impurities)

Hardness: 6.5-7 on Mohs scale; Color: Orange, reddish-brown, semi-transparent; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline chalcedony); Cleavage: None; Specific gravity: 2.58-2.64

Hardness: 6
Color: Orange, reddish-brown, semi-transparent
Luster: Vitreous to waxy

Identified July 18, 2026More gemstone →

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Physical properties

Formation & geological history

Forms in volcanic rocks at low temperatures, filling cavities and veins. The orange color is due to iron oxide impurities. It occurs in areas of volcanic activity and along certain riverbeds.

Uses & applications

Primarily used in jewelry (beads, cabochons), ornamental carvings, and as a popular tumbled stone for collectors and metaphysical practices.

Geological facts

Carnelian has been used for over 4,500 years; it was highly prized by the ancient Egyptians for amulets and by Romans for signet rings because hot wax does not stick to it.

Field identification & locations

Identify by its translucent to semi-opaque orange-red body and lack of visible crystalline structure. Common locations include Brazil, India, Uruguay, Madagascar, and the USA (PNW).

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Diamond and Gold Jewelry

Carbon (Diamond) / Au (Gold)

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Cubic Zirconia (simulant) or Diamond

ZrO2 (Cubic Zirconia) or C (Diamond)

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Ammolite

Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)

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Cubic Zirconia (or possibly Diamond)

Zirconium dioxide (or Carbon)

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Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

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Faceted Gemstone

Unknown transparent mineral, possibly Diamond (C), Cubic Zirconia (ZrO2), Quartz (SiO2), or Glass

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